Mail is being delivered after 5 p.m. more than two-thirds of the time to residents and businesses in the District and the Maryland suburbs, an investigation released Tuesday found, raising concerns about the safety of letter carriers and provoking a deluge of complaints from customers.

The number of letter carriers who are still on their routes after 5 p.m., even in the winter darkness, and the delayed delivery of letters and packages has grown so dramatically in recent years that the Capital District now ranks as the worst area in the country for late mail service, a report by Postal Service Inspector General David Williams concluded.

Northern Virginia also ranked in the top five areas of the U.S. where Americans received their mail late, auditors found, with 69 percent still on their routes late in the day during fiscal year 2013.

Both regions were well above the national average for late mail delivery, which was 38 percent last year.

The delays violate the post office’s goal of having 95 percent of city carriers return from street operations before 5 p.m. to maximize the efficiency of the long logistics chain of mail delivery. The Capital District pays $4.5 million a year in overtime for carriers who are out late, the inspector general found previously.

The probe of delivery after dark in the Washington area was prompted by the death last November of a part-time carrier who was fatally shot in Prince George’s County as he was delivering the mail at 7:30 p.m. No arrest has been made in the killing of Tyson Jerome Barnette, a part-time carrier who relieved full-time carriers of excess workloads.

The delivery delays have resulted from a cascade of service cuts as the mail agency, reeling from multi-billion-dollar losses as Americans turn more and more to the Internet to correspond and do business, has shaved costs.

Postal officials have drastically reduced the size of the workforce in recent years, from letter carriers to postal clerks, replacing thousands of carriers with part-time contract workers. The agency has also closed hundreds of mail sorting plants, several of them in the Washington area.

The cuts have led to disruptions in the complex journey that letters, magazines and packages take from senders to homes and businesses, with the result that mail arrives late at local post offices from overburdened processing hubs, some of it not fully sorted, auditors found. Letter carriers often are left to finish the sorting by hand, delaying them from getting out on their routes.

Supervisors routinely fail to monitor and fix the problems, leaving a chaotic system that’s left angry customers who say they still rely on prompt mail delivery to receive important documents and correspondence. Carriers who are still on their routes at night, along with postal unions that represent them, say they are concerned about their safety in high-crime neighborhoods after dark.

“With the increase in carriers delivering mail after 5 p.m. comes increased risks to safety,” the inspector general wrote. “Each day some carriers deliver mail to locations that could be considered unsafe and deliveries late in the day can exacerbate potential dangers.”

Postal officials announced plans last month to accelerate their closures of mail sorting plants across the country to save more money, a step that could result in continuing delivery issues. In the last 18 months or so, the agency has quietly changed its service standards in many parts of the country to accommodate the closures, increasing the amount of time allowed for a letter to travel from one end of the country to the other by one day and sometimes two.

The number of carriers delivering mail at night in the Capital District, which encompasses Washington, Prince Georges, Charles, Calvert, and St. Mary’s counties, as well as most of Montgomery and of Anne Arundel counties, grew 14 percent from the first quarter of 2011 to the last quarter of 2013, auditors found. In those three months alone, 100,239 carriers on close to 2,000 routes delayed their deliveries.

In recent years the Postal Service has heard from an increasing number of Americans about chronic problems with late and missing mail. The agency received 122,138 complaints from across the country about late mail delivery in the second quarter of 2014, the highest number since the last quarter of 2011, when 79,709 complaints came in, according to data provided to the Washington Post under the Freedom of Information Act. The complaints went down in the second quarter, to 84,700.

A large part of the problem appears to be a deluge of mail from closed sorting plants. Two plants closed in the Washington region in recent years. Auditors found that supervisors didn’t plan properly for a flood of new pieces of mail and didn’t use the more effective processes for organizing it to ensure that it arrives at local post offices early enough in the morning for letter carriers to pick up the mail on their route and start driving.

The Postal Service’s goal is for 95 percent of city letter carriers to return from street operations before 5 p.m.

Postal Service officials told the inspector general they are working to change the way the flow of work is structured and improving supervision and training for employees in the Washington area. The efforts include reevaluating staffing levels, route structures and start times, and adjusting volume arrival issues arising from processing facilities.

“Employee safety is a top priority at the U.S. Postal Service,” the agency said in a statement. “We have a robust safety program to heighten awareness of the range of situations carriers may face while performing their duties, and we teach techniques to minimize risks to them.”

The agency said it is making investments in technology to allow supervisors to communicate in real time with carriers. But “later-day deliveries are sometimes unavoidable due to inclement weather, traffic issues or other unplanned events, as well as seasonal fluctuations in mail volumes,” it said.

The statement also said the “needs of our customers are changing, which means USPS will continue to adjust delivery operations to meet these needs,” but did not elaborate.

Prince George’s County police and the Postal Inspection Service say they are continuing to investigate Barnette’s killing and have offered up to $125,000 in reward money for tips that lead to a break in the case. Both agencies declined to share details of the investigation.

“We’ve been frustrated since day one, but there isn’t anything we can do about it except pray,” Katherine Strong, Barnette’s grandmother, said recently. “I don’t understand why anyone would shoot him like that.”

Lisa Rein covers the federal workforce and issues that concern the management of government.

Lynh Bui is a Prince George's County public safety reporter and former Montgomery County education reporter.

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